Builder | Padrões de Projeto | Python

Builder | Padrões de Projeto | Python

Exemplo

Classe que faz toda a construção sem usar o builder

class HTTPRequest:
    """The product - what we're building"""
    def __init__(self, url):
        self.url = url
        self.method = "GET"
        self.headers = {}
        self.body = None
        self.timeout = 30
        self.auth = None
        self.verify_ssl = True
        self.allow_redirects = True
        self.max_redirects = 5
        self.cookies = {}
        self.proxies = {}

    def execute(self):
        """Simulate executing the request"""
        auth_str = f" (auth: {self.auth[0]})" if self.auth else ""
        return f"{self.method} {self.url}{auth_str} - timeout: {self.timeout}s"

Refatorando

class HTTPRequestBuilder:
    """The builder - constructs HTTPRequest step by step"""
    def __init__(self, url):
        self._request = HTTPRequest(url)

    def method(self, method):
        """Set HTTP method (GET, POST, etc.)"""
        self._request.method = method.upper()
        return self  # Return self for method chaining

    def header(self, key, value):
        """Add a header"""
        self._request.headers[key] = value
        return self

    def headers(self, headers_dict):
        """Add multiple headers at once"""
        self._request.headers.update(headers_dict)
        return self

    def body(self, body):
        """Set request body"""
        self._request.body = body
        return self

    def timeout(self, seconds):
        """Set timeout in seconds"""
        self._request.timeout = seconds
        return self

    def auth(self, username, password):
        """Set basic authentication"""
        self._request.auth = (username, password)
        return self

    def disable_ssl_verification(self):
        """Disable SSL certificate verification"""
        self._request.verify_ssl = False
        return self

    def disable_redirects(self):
        """Disable automatic redirects"""
        self._request.allow_redirects = False
        self._request.max_redirects = 0
        return self

    def build(self):
        """Return the constructed request"""
        return self._request

# Now using the builder is much cleaner and more readable
request = (HTTPRequestBuilder("https://api.example.com/users")
    .method("POST")
    .header("Content-Type", "application/json")
    .header("Accept", "application/json")
    .body('{"name": "John", "email": "john@example.com"}')
    .timeout(60)
    .auth("username", "password")
    .disable_redirects()
    .build())

print(request.execute())
print(f"\nHeaders: {request.headers}")
print(f"SSL verification: {request.verify_ssl}")
print(f"Allow redirects: {request.allow_redirects}")

Output

Headers: {'Content-Type': 'application/json', 'Accept': 'application/json'}
SSL verification: True
Allow redirects: False

Exemplo​

Exemplo